1. Field of the Invention
The invention relates to a process for consolidating beds of particulate solids that include some water into unitary porous solids. The invention also relates to various useful cleaning products, especially mildly acidic to strongly alkaline textile, dishwashing, and surface care cleaning products in porous solid form, which can be made by the process. Still another aspect of the invention relates to using the novel solid detergents, cleaners, soaps and surface care products.
A product according to this invention is a xe2x80x9cmacrosolidxe2x80x9d, i.e., it is a unitary solid three dimensional object that is (i) capable, at a minimum, of retaining a definite shape and size under the influence of the normal ambient gravitational field at the surface of the earth and of being moved as a unit by forces exerted at only one end or edge thereof and (ii) sufficiently large to include within itself at least one hypothetical cube having dimensions of 2.5 millimeters (hereinafter often abbreviated xe2x80x9cmmxe2x80x9d) on each edge. Preferably, with increasing preference in the order given, a macrosolid product according to the invention is sufficiently large to include within a single product a hypothetical cube having a length of 5, 6.5, 8.2, 10.0, 12.1, or 13.0 mm on each edge. A macrosolid thus contrasts with a conventional granular or powdered solid material, in which each unitary particle is normally no more than 2.2 mm in at least one of its three principal geometric dimensions. (Granular or powdered solid cleaners are often preferred for domestic use, where the amount of cleaning power required often is highly variable from one use of the cleaner to the next. However, granular or powdered cleaners require the performance of a separate volume or mass measuring step in order to give reproducible results and efficient use of the cleaner. Therefore, under industrial or other conditions where the amount of cleaning power needed from one use of a cleaner to the next is fairly constant, and/or the value of time saved is more economically important than the possible waste of small amounts of cleaner, macrosolid cleaners are generally preferred, because a worker can quickly select and use some small integral number, usually one, of the macrosolid cleaners for each instance of use, without the need for any more time-consuming measurement step.)
The units of the macrosolid cleaner according to this invention are commonly called xe2x80x9ctabletsxe2x80x9d or xe2x80x9cblocksxe2x80x9d, and these terms are used herein for convenience in description but are not to be understood in and of themselves to imply anything about the content, strength, or application of the particular formulation. Smaller macrosolids on the order of 10 to 50 grams in mass are generally referred to as xe2x80x9ctabletsxe2x80x9d because such relatively small macrosolids often are cylinders with a height substantially less than the diameter, while larger macrosolids with masses on the order of 100 grams (hereinafter often abbreviated xe2x80x9cgxe2x80x9d) to several kilograms (hereinafter often abbreviated xe2x80x9ckgxe2x80x9d) are generally referred to as xe2x80x9cblocksxe2x80x9d. Unless explicitly further qualified, however, neither xe2x80x9ctabletxe2x80x9d or xe2x80x9cblockxe2x80x9d should be understood herein as having any quantitative implications.
2. Discussion of Related Art
Mildly acidic to strongly alkaline cleaners and detergents find wide application in the form of powders, granulates, tablets, pastes, and blocks. Tablets and blocks in the prior art have generally been made by pressing of powdered solids or of paste-like slurries of such solids, or by molding of molten constituents or of slurries of partially solid constituents in some liquid that readily fills a mold. Many prior art processes for the production of solid cleaning products or molded cleaners, for example, require heating and mixing of the raw materials and/or aqueous solutions in order to insure homogeneity in the final product. In addition, thickening, pouring, and cooling of the heated mixtures either alone or with the use of molds or forms may also be required.
Most conventional prior art techniques for the production of tablets or molded cleaners suffer from the disadvantage that they require the addition of certain additional auxiliaries, such as tabletting aids, which must be added to the raw materials. These aids are required in order to stabilize the active ingredients to form a slurry or paste mixture for further processing such as melting, pouring or being pressed into the final desired product form. Such auxiliaries add no cleaning power or other desired properties to the final product, but yet are often required to enable raw materials to be conveniently pumped or otherwise conveyed within a process, or to facilitate heat transfer where raw materials exhibit different degrees of heat stability. The use of such auxiliaries may also contribute to delivery and dissolving problems. The use of tabletting aids also is disadvantageous because it increases both raw materials and manufacturing costs.
The development of a process that did not involve increased pressures, or heating, pumping, pouring, cooling of melts, and the like, with the attendant required steps could potentially streamline the manufacturing process of solid detergents and cleaners. Moreover, a savings of raw materials could also be realized if the addition of components that are required solely for handling or heat stabilization purposes were no longer required. Newer methods have been sought to overcome these disadvantages. Currently, there is also a desire for higher performance products, which implies the use of lesser quantities of auxiliaries and therefore greater quantities of active components in smaller volumes. This gives rise to what is perceived as a xe2x80x9cstrongerxe2x80x9d product. The result is the tendency towards more concentrated raw materials mixtures which, during the course of manufacture, may exist as fluids and/or molten streams, with attendant handling and processing concerns. It would therefore be advantageous to develop a process for the manufacture of detergent or cleaner products that demonstrated the required efficacy and featured ease and greater convenience in raw material handling and processing.
It is therefore an object of the present invention to provide a process for the formation of solid tablet or block cleaning formulations directly from powder or granular raw material mixtures.
It is also an object of the present invention to provide a process for the formation of solid tablet or block cleaning formulations directly from powdered or granular raw material mixtures which does not require the bulk melting of raw material mixtures, and which accommodates certain useful constituent materials that may be impractical to use in a melt process because of temperature sensitivity or related considerations.
It is a still further object of the present invention to provide an alternate process and associated formulations for the production of macrosolid detergents or cleaners in which the need for non-active ingredients such as ballast, fillers, tabletting aids, and the like is eliminated or at least reduced.
Still other objects of this invention will become apparent from the description below.
Other than in the operating examples, or where otherwise explicitly indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term xe2x80x9caboutxe2x80x9d in describing the broadest scope of the invention. Practice within the numerical limits given, however, is generally preferred.
Also, unless there is an explicit statement to the contrary, the description below of groups of chemical materials as suitable or preferred for a particular ingredient according to the invention implies that mixtures of two or more of the individual group members are equally as suitable or preferred as the individual members of the group used alone. Furthermore, the specification of chemical materials in ionic form should be understood as implying the presence of some counterions as necessary for electrical neutrality of the total composition. In general, such counter ions should first be selected to the extent possible from the ionic materials specified as part of the invention; any remaining counterions needed may generally be selected freely, except for avoiding any counterions that are detrimental to the objects of the invention. Also, unless otherwise specified, figures expressed in terms of xe2x80x9cpercentxe2x80x9d or xe2x80x9c%xe2x80x9d are to be understood as percent by weight.
It has surprisingly been discovered that high frequency electromagnetic energy in the subinfrared range may be utilized for the rapid formation of macrosolids from a volume of more to less tightly packed powder or granular raw material(s), when at least part of these raw materials contain reversibly bound water, and that this process may be used to produce particularly useful mildly acidic to strongly alkaline cleaners in macrosolid form. An important feature of the invention is that reusable molds or xe2x80x9creceptacle moldsxe2x80x9d can be employed to enable the formation of tablets or block macrosolids with excellent reliability and reproducibility. An advantage of the technique is that it eliminates the need for forming intermediate bulk molten or fluid phases and also eliminates the alternative need for high pressure compression in order to generate the final macrosolid product form. A further advantage of the invention is that certain components, which heretofore could not practically be included in tablets produced by the prior art technique of forming tablets under pressure, may be incorporated directly into the macrosolids formed.
In this description, the term xe2x80x9ccleanerxe2x80x9d or xe2x80x9ccleaning compositionxe2x80x9d includes any substance that can readily be used to clean a hard surface or a textile, and thus includes compositions otherwise known as detergents, cleaners, all-purpose cleaners, scouring cleaners, pre-soak, and pre-wash products, whether formulated for domestic, institutional, or industrial application or for manual or automatic laundry washing and dishwashing, ware-washing, surface washing, floor care, hard surface cleaning, or the like in any shape.
The term xe2x80x9chydratedxe2x80x9d as used herein is to be understood as qualified implicitly, if not explicitly, to mean xe2x80x9chydrated at particular conditions of temperature, pressure, and relative humidity of the atmosphere to which it is exposed or with which it is in equilibriumxe2x80x9d, and if these conditions are not specified explicitly, they are to be understood as those of the ambient atmosphere in a space within which the temperature is maintained within the normal range for human comfort, i.e., 18-30xc2x0 C., and the relative humidity is between 5 and 95%, and further as implying that at least one of the following characterizations of the material is true: (i) The material is a solid including stoichiometrically well characterized water of hydration or (ii) the material is liquid and/or solid with a definite measurable mass and, if the temperature of the material is raised by a sufficient amount above the reference temperature at which the material is hydrated, and/or if the pressure and/or relative humidity of the gaseous atmosphere to which the material is exposed is lowered by a sufficient amount from that with reference to which the material is hydrated, the mass of water vapor in the atmosphere to which the material is exposed will be increased and the mass of the solid and/or liquid formerly hydrated material will decrease by an amount that is not more than 120%, or preferably, with increasing preference in the order given, not more than 115, 109, 106, 103 or 101, % of the amount by which the mass of the water vapor in the gaseous atmosphere to which the formerly hydrated material is exposed has increased.
Normally, the above specified transfer of mass from the solid and/or liquid hydrated material to a water vapor containing gaseous phase, in order for the material to be useful in this invention, must occur to a measurable extent within 24 hours, or, with increasing preference in the order given, will occur within 8, 5, 2, 1, 0.5, 0.2, 0.09, or 0.005, hours after a change including at least one of the following conditions: The temperature is raised by 50xc2x0 C.; the pressure is reduced by 100 millibars; and/or the relative humidity is reduced by 20%.
Microwaves, as described in the co-pending ""728 application, have frequencies above 300 megahertz (hereinafter often abbreviated as xe2x80x9cMHzxe2x80x9d), and are generally regarded as having frequencies in the range of 300 to 300,000 MHz. Microwaves essentially belong to the broader range of electromagnetic radiation herein referred to as xe2x80x9csubinfrared electromagnetic radiationxe2x80x9d or xe2x80x9cSERxe2x80x9d, the latter which have frequencies ranging from 3 to 300,000 MHz. The remaining band in this portion of the electromagnetic spectrum is known as the xe2x80x9cradio wave [or xe2x80x98frequencyxe2x80x99]rangexe2x80x9d, and has frequencies in the range of 3 to 300 MHz. Microwaves are therefore very small radio waves. According to the present invention, it is possible to use subinfrared electromagnetic radiation of either range, microwave or radio wave, to form the macrosolids further described below.
The term xe2x80x9cmicrowave treatment [or xe2x80x98irradiationxe2x80x99]xe2x80x9d or xe2x80x9ctreatment by [or xe2x80x98irradiation withxe2x80x99] microwavesxe2x80x9d as used herein refers to the exposure of a raw material or mixture thereof to electromagnetic energy of the microwave region. The term xe2x80x9csubinfrared electromagnetic energy (hereinafter often abbreviated xe2x80x98SERxe2x80x99)xe2x80x9d, xe2x80x9ctreatment [or xe2x80x98irradiationxe2x80x99]xe2x80x9d or xe2x80x9ctreatment by [or xe2x80x98irradiation withxe2x80x99] subinfrared electromagnetic energyxe2x80x9d as used herein refers to the exposure of a raw material or mixture thereof to high frequency electromagnetic fields of wavelengths from 3 to 300,000 MHz. The words xe2x80x9cexposurexe2x80x9d or xe2x80x9ctreatmentxe2x80x9d in connection with xe2x80x9csubinfrared electromagnetic radiationxe2x80x9d or xe2x80x9cSER energyxe2x80x9d are also to be understood to be generally synonymous within this context. Where it is necessary to further distinguish between lower frequency subinfrared electromagnetic energy (i.e., radio waves or xe2x80x9cRWxe2x80x9d energy, which is generally understood to mean about 3 to about 300 MHz), and higher frequency subinfrared electromagnetic energy (microwave range energy or xe2x80x9cMWxe2x80x9d energy, which is generally understood to mean about 300 to about 300,000 MHz) appropriate distinction will be made within the text.
For almost all non-conductive or dielectric chemical compounds that are stable at normal ambient temperatures of 18-30xc2x0 C., subinfrared electromagnetic energy is nonionizing, and can cause motion of some atoms in a material with respect to other atoms in the material by migration of ions, rotation of molecules with dipole moments, or polarization of molecules with the high frequency electromagnetic field. Exposure to subinfrared electromagnetic radiation does not cause permanent changes in chemical bonding. Although the permitted radio frequencies vary from country to country, the most common frequencies for industrial, scientific and medical use (ISM bands) for radio frequency include 13.56 and 27.12 MHz, while those for microwave frequency are 896 MHz and 2450 MHz.
The terms xe2x80x9cparticlesxe2x80x9d, xe2x80x9cparticulate matterxe2x80x9d, and xe2x80x9cpowder(s)xe2x80x9d imply, unless explicitly stated to the contrary, that the material so described is in the solid phase. A xe2x80x9cbedxe2x80x9d of particulate matter means a collection of particles that, by virtue of mutual physical support among the particles, and, optionally, between some of the particles and at least part of the wall or walls of a container for the bed and/or a solid insert within the bed, has a gross shape that does not change and a size that does not decrease by motion of the some of the constituent particles with respect to others of the constituent particles under the influence of the ambient gravitational force at the surface of the earth, in the absence of any localized vibration of the bed.
In addition to the solid particles in the bed, there may also be some liquid raw material in the bed, so long as the volume of liquid relative to the volume of solid in the bed is not so large as to excessively facilitate the motion of the solid particles in the bed with respect to one another, so as to cause the bed to fail to satisfy the conditions of having a gross shape and size unchanging under the influence of gravity as specified above.
The container in which a particle bed is present may be as simple as a flat sheet on which a bed of particles rests, although ordinarily it will also have walls that offer some lateral support to the particle bed. The bottom and walls if any of the container may be of any material adequate to support the particle bed, i.e., not sufficiently porous that the particles can pass through it under the influence of gravity and the pressure of overlying parts of the particle bed.
The material chosen for the container used according to the present invention may be any subinfrared electromagnetic radiation-compatible and subinfrared electro-magnetic radiation-penetrable material and, in those processes where higher temperatures are achieved, preferably is a material that is capable of withstanding temperatures up to, e.g., 160xc2x0 C. For processes starting from raw material beds containing NaOH in concentrations greater than 75 percent, polystyrene or polyethylene molds preferably are not used because of the danger of melting them. The material chosen for the container or mold should also be one which can be formed into and maintain the desired shape throughout repeated use, if such is desired. Suitable reusable container materials include glass, polyethylene, polypropylene, plastic, ceramics, or composites thereof, or any other SER-compatible material at the particular temperatures achieved, depending upon formulation of the starting raw materials. In those instances where the raw material mixture contains corrosive components, it is preferable to use a container made of material resistant to the corrosive effect of the contents. Plastic films, including water soluble films, may be effectively used as one time containers, which can be sealed after formation of the macrosolid product within them and serve as a shipping and dispensing container for the product.
The xe2x80x9cbulk volumexe2x80x9d of a bed of particulate matter or of a porous solid means the volume of the smallest pore- and interstitial space-free solid that could be formed by filling all the pores and interstitial spaces of the bed or porous solid, and the xe2x80x9cpore volumexe2x80x9d of a particle bed or porous solid means the total volume required to fill all the pores and interstitial spaces of the bed or porous solid to form such a smallest pore- and interstitial space-free solid. The xe2x80x9cdensityxe2x80x9d of a bed of particulate matter or of a porous solid means the ratio of the mass of the total of solid and liquid phases contained within the bed or porous solid to the bulk volume of the bed or porous solid.
In one major embodiment, a process according to this invention comprises steps of:
(A) providing a container with walls penetrable by subinfrared electromagnetic radiation and having within the container a bed of particles of raw material, at least part of said raw material being a hydrated material; and
(B) irradiating the bed of particles provided in step (A) for a sufficient time with subinfrared electromagnetic radiation of sufficient energy to cause the temperature of at least part of said raw material to rise, and subsequently discontinuing the irradiation of raw material and cooling, so as to transform the bed of particles into a macrosolid within said container, said macrosolid having a bulk volume not greater than 1.20 times, or with increasing preference in the order given, not more than 1.15, 1.11, 1.08, 1.05, 1.03, 1.01, or 1.00 times, the bulk volume of the particle bed from which it was formed.
It is known that exposure to electromagnetic energy in the microwave range will cause water molecules to experience an increase in rotational energy, which may subsequently be imparted to neighboring molecules or ions in the form of heat. Similarly, electromagnetic energy in the radio wave range will cause the dipoles within molecules of a susceptible material to try to orient or align themselves with the electromagnetic field, thus gaining energy. Because this field typically reverses in excess of 10 million times a second (10 MHz), internal friction takes place among the molecules, which can subsequently be imparted to neighboring molecules or ions in the form of heat. Particle beds processed according to this invention in fact usually become heated while being irradiated with subinfrared electromagnetic energy.
The phenomenon of using subinfrared electromagnetic energy is also known as dielectric heating, which is distinct from conventional heating. Conventional heating has to be applied externally and penetrates into a material by conduction. Dielectric heating, on the other hand, produces heating directly within the material, because all the molecules of the material are simultaneously exposed to high frequency electromagnetic fields. Therefore, the xe2x80x9ccoolingxe2x80x9d described as part of step (B) above normally begins as soon as subinfrared electromagnetic irradiation is discontinued, and does not normally imply any special cooling machinery, although such could be used if desired.
Furthermore, in those instances where microwave treatment can suffer from the attenuation problem discussed above, dielectric heating using subinfrared electromagnetic energy can be advantageous since all the molecules in a sample may be faster and more uniformly treated via this technique. For each material, there is a quantitative susceptibility to the heating effects of high frequency electromagnetic energy, which can be measured as a function of frequency, and generally varies considerably depending on the frequency. Every material or material mixture therefore normally has an optimum frequency at which it is most receptive to SER energy. Theoretically, this optimum frequency is the one that should be selected for SER irradiation.
The amount of energy that a material absorbs at subinfrared electromagnetic frequencies is known as its dielectric loss factor, ∈xe2x80x3, which is the product of the dielectric constant, ∈, and loss tangent, tan xcex4. At the molecular level, the loss tangent can be considered as an indication of the average xe2x80x9cfrictionxe2x80x9d effect contributed by each polarized component, and is measured as the tangent of the phase angle between the field in the material and the applied field. Water has a very high loss factor, and is therefore particularly receptive to dielectric treatment with SER energy. By way of comparison, the dielectric loss factor for water (0.1 molal NaCl) is 18 at 3,000 MHz (microwave range), but it is 100 at 10 MHz (radio wave range). Most remaining raw material(s) of the present invention generally have much lower loss factors, and therefore will be relatively unaffected by SER irradiation. This provides a useful limiting mechanism in many situations.
Scanning electron microscopy (xe2x80x9cSEMxe2x80x9d) studies of macrosolids formed according to this invention, particularly those exposed to microwave irradiation, show a xe2x80x9cbridgeworkxe2x80x9d structure, in which the originally individual particles have been joined by sufficiently thick xe2x80x9cbridgesxe2x80x9d to join the former particle bed into a unitary macrosolid. The macrosolid thus formed can simultaneously be described both as xe2x80x9chardxe2x80x9d and xe2x80x9cporousxe2x80x9d, due to the presence of interstitial spaces as part of this bridgework structure. While applicants do not wish to be bound by any particular theory, they believe that the heat induced in the particle bed during irradiation, perhaps accompanied by volatilization of some of the water initially present, causes a localized sintering of hydrated species alone and/or accompanied by a concomitant temporary dissolution of other species present in the raw material to form xe2x80x9cbridgesxe2x80x9d between the initially separate particles in substantially single point contact. This bridged-type structure may account for the surprising strength and structural integrity of the macrosolids formed during most processes according to the invention.
The application of a process according to this invention to a particle bed comprised predominantly of water soluble alkaline cleaning agents produces porous macrosolids with unique combinations of properties that are valuable in many applications. Accordingly, another major embodiment of this invention is a macrosolid article having the following characteristics:
(A) at least half, or more preferably at least 60%, of the mass of the macrosolid article consists of material selected from the group consisting of alkali metal and alkaline earth metal salts of sulfates (including hydrogen sulfates), carbonates (including hydrogen carbonates and acid carbonates, also called bicarbonates), silicates (including zeolites and metasilicates), phosphates (including hydrogen phosphates and condensed phosphates such as pyrophosphates and tripolyphosphates), hydroxides, borates, and citrates, with the alkali metal salts generally being preferred;
(B) at least half of the mass of the macrosolid consists of chemical species that are solid at 25xc2x0 C. and are soluble in water at 25xc2x0 C. to form solutions containing at least 10 grams per liter of the dissolved solid chemical species; and
(C) upon immersion at 55xc2x0 C. in a volume of water that is at least ten times the bulk volume of the macrosolid, the macrosolid dissolves, disintegrates, or both dissolves and disintegrates, so that no part of the macrosolid remains in any single undissolved particle having a largest dimension greater than 2.2 mm, within a time after immersion that is not greater than 0.050 minutes, or with increasing preference in the order given, not greater than 0.042, 0.036, 0.031, 0.027, 0.020, or 0.010 minutes, per cubic centimeter of bulk volume of the macrosolid.
A significant advantage to the tablet or block product formed according to the process of the present invention is that additional pre-treatment processing steps, such as pre-heating the raw material mixtures, fluidizing mixtures, pumping heated fluids, or continuously sweeping streams of hot air through the microwave or radio wave treatment chamber, are not required. Another advantage of the macrosolid tablets and blocks formed according to the present invention is that a dissolving or pre-use step is not required. The macrosolid tablet or block may be introduced directly into the cleaning space in which the product is ultimately used, especially in the areas of industrial and household cleaning, and particularly with respect to laundry and dishwasher applications.
As used herein, the term xe2x80x9ccleaning spacexe2x80x9d is intended to encompass any space in which there is contact between a solid surface, including a textile, and a liquid, liquid slurry, or paste cleaning composition with the result that some soil material, the presence of which is undesired on the solid surface, is transferred to the cleaning composition. Thus, the cleaning space may be the tub or interior space of a clothes or dishwashing machine, a spray zone of an industrial bottle washing machine, a sink for manual dishwashing, a floor or wall and the space immediately surrounding the part of it to be cleaned, the exterior surface of a solid object and the space immediately surrounding the part of the exterior surface to be cleaned, and the like. In many cases, the cleaning composition is supplied to the cleaning area from a reservoir, which may be a stock tank in a washing machine, a spray bottle, a mop bucket, or the like.
Still another embodiment of the invention is the use of macrosolid cleaning products as described above in cleaning any of the wide variety of materials noted above. In particular, many of the macrosolid cleaner embodiments of the invention are well suited for use in a dispensing device and method of use as described in FIGS. 4 and 6-9 and in the text from column 9 line 47 through column 16 line 31 of U. S. Reissue Pat. No. 32,763 of Oct. 11, 1988 to Fernholz et al., which portions of said U.S. Re. Pat. No.32,763 are, to the extent not inconsistent with any explicit description in this specification, hereby incorporated into this specification by reference, mutatis mutandis; in particular, the terms xe2x80x9ccast blockxe2x80x9d and the like in the incorporated portions of U.S. Re. Pat. No. 32,763 are to be understood as replaced herein by xe2x80x9cmacrosolid cleanerxe2x80x9d according to this invention as described above, or a solid cleaner modified by imbibition of additional material into a porous macrosolid cleaner according to this invention as described above.
The porous macrosolids produced according to the invention are also valuable in another application area. Many cleaners currently on the market exist in liquid form as concentrates or so-called cleaner xe2x80x9cenhancersxe2x80x9d which may contain alcohol or other organic solvents. When combined with water in a use situation, a number of cleaners suffer from such undesirable phenomenon as phase separation and salting- or settling-out in solution. Other cleaners incorporate supplemental additives or require formulations with high water content in order to keep materials in solution during storage, transportation, etc. One disadvantage in such instances is that it is costly to transport and provide additional packaging materials for the larger required product volumes.
Certain attendant disadvantages of existing cleaner products may be overcome by combining active components just prior to the dissolution and use of a solid cleaner, such that there is insufficient opportunity for components to phase separate or fall out of solution. The macrosolids of the present invention are particularly adaptable to such an application because, as described briefly above, some of the macrosolid tablets or blocks formed according to the subinfrared electromagnetic radiation process of the current invention exhibit remarkably rapid dissolution, or a combination of dissolution and mechanical disintegration upon exposure to water. Accordingly, another major embodiment of this invention is a two-component or dual-pack article comprising:
(A) a solid first component, wherein said first component consists of a macrosolid tablet or block prepared according to the process of the invention; and
(B) a liquid second component, wherein said second component consists of at least one fluid component, and which further may optionally contain dissolved solid substances.
In one preferred embodiment of the invention, the macrosolid tablet or block and liquid component are individually added, or combined and then added, to an appropriate amount of water to produce the desired cleaning solution for a particular cleaning application just prior to use. As used herein, the term xe2x80x9cjust prior to usexe2x80x9d is meant to indicate that after the macrosolid first component and liquid second component have been combined with water in preparation for use, the resulting cleaner is preferably used within a time that is not greater than 480 minutes, or with increasing preference in the order given, not greater than 240, 120, 60, 30, 15, 5, 1, 0.50, 0.25, 0.10, 0.05, 0.025 or 0.01 minutes of the time at which the solid first component and liquid second component are first combined with water.
A particular advantage of the dual-pack product according to the present invention is that it permits the incorporation of certain liquids and dissolved solid substances into a liquid phase of a cleaning formulation, which for practical purposes cannot readily be incorporated into the solid first component. By way of illustration, such substances might include liquid waxes or silicones which are desirable in cleaners in the floor care area, for example.
Typical hydrated materials suitable for use in a process according to this invention include materials that contain water of crystallization or hydration, i.e., water molecules, present in a solid in definite stoichiometric ratio to another chemical constituent of the solid, which can be expelled in whole or in some stoichiometrically well defined part by raising the temperature of the solid and/or lowering the amount of water vapor in the gaseous atmosphere to which the solid is exposed past a specific threshold value; and materials, such as the alkali metal hydroxides, that, without necessarily having any definite stoichiometric hydrates, may contain xe2x80x9cfreexe2x80x9d water molecule(s) in some more general association with the solid in continuously variable amounts down to near zero.
Particular hydrated compounds useful in the practice of this invention include alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide; sulfates, such as magnesium and sodium sulfate; silicates, such as sodium metasilicate; phosphates, such as sodium tripolyphosphate or trisodium phosphate; carbonates, such as sodium or potassium carbonate; bicarbonates, such as sodium or potassium bicarbonate; and borates, such as sodium borate; etc.
A particularly preferred group of stoichiometrically well characterized hydrated materials useful in this invention includes sodium metasilicate pentahydrate (Na2SiO3.5H2O), sodium carbonate decahydrate (Na2CO3. 10H2O), sodium tetraborate tetrahydrate (borax, Na2B4O7.10H2O), trisodium phosphate dodecahydrate (Na3PO4.12H2O), and sodium tripolyphosphate hexahydrate (Na5P3O10.6H2O).
In some applications of the invention, it is preferred to include in the raw material in the particle bed at least 4% by volume, or with increasing preference in the order given, at least 6, 10, 16, or 25% by volume, but not more than 35% by volume, of solid material that melts at the temperature actually reached during irradiation according to processes of the invention. This readily melted material may or may not be hydrated, but often is hydrated. For example, it has been observed that borax, trisodium phosphate dodecahydrate and sodium hydroxide monohydrate all melt readily under microwave irradiation.
A process according to the invention utilizes as one of its inputs a plurality, usually a large plurality, of relatively small particles, which may be called powder, granules, prills, or some similar term, to make a relatively large unitary solid. In most examples of practical interest, the relatively small particles used are sufficiently small that it is impractical to count and characterize each of them individually. Therefore, all specifications herein that refer to quantitative geometrical characteristics of individual raw material particles are to be understood as satisfied by consideration of a sufficient number of individual particles as to give statistical assurance at the 90% confidence level or higher that the average of the specified geometrical characteristic for the entire particle distribution is within 10% of the value specified.
For the purposes of this description, the xe2x80x9clargest dimensionxe2x80x9d of any unitary solid body means the largest distance possible between two hypothetical parallel planes both of which are touched by the solid body, while the xe2x80x9csmallest dimensionxe2x80x9d of the unitary solid body is the distance between the closest of all possible pairs of two hypothetical parallel planes between which the solid body can fit. Preferably, with increasing preference in the order given, the ratio between the largest dimension and the smallest dimension of the particles utilized as raw material in a process according to this invention is not greater than 10:1, 5:1, 2.0:1.0, 1.8:1.0, 1.55:1.00, 1.42:1.00, 1.33:1.00, 1.25:1.00, 1.18:1.00, 1.11:1.00, or 1.06:1.00.
Also, independently, with increasing preference in the order given, the ratio of the smallest dimension of the macrosolid made by a process according to this invention to the smallest dimension of the raw material particles used to make it is at least 5:1, 10:1.0, 30:1.0, 120:1.00, or 600:1.00. This condition shall be considered to be satisfied if satisfied for the smallest dimension of the raw material particles used as determined by a statistical analysis as described above, or alternatively if satisfied by an xe2x80x9calternative smallest dimensionxe2x80x9d defined by the maximum size of the openings in a screen, cloth mesh, or like structure that has openings of a known maximum size and through which all the particles in the particle bed have been passed. Independently, it is preferred that the average size of the raw material particles used fall within the range from 1 xcexcm to 2 mm, more preferably from 0.10 to 1.2 mm, or still more preferably from 0.10 to 0.5 mm. Independently, it is preferred that the maximum particle size of the solids used in the raw material not be, with increasing preference in the order given, greater than 1.0, 0.84, 0.71, 0.60, 0.50, 0.42, 0.35, 0.30, 0.25, 0.21, 0.18, 0.15, 0.13, 0.10, 0.088, 0.074, or 0.063 mm.
Also, independently, with increasing preference in the order given, it is preferred that at least 60, 70, 80, 87, 92, 97, or 99% of the volume of the bed of particles utilized in a process according to this invention be solid rather than liquid at the temperature of the bed before beginning irradiation with subinfrared electromagnetic energy; and, independently, that the pore volume of the particle bed utilized in a process according to the invention fall within the range of from 1 to 50, 3 to 45, 5 to 40, 7 to 35, 10 to 30, 13 to 28, 15 to 26, or 17 to 25, % of the bulk volume of the particle bed. Independently, it is also preferred that the pore volume of the macrosolid formed at the end of process step (B) as defined above in a process according to the invention fall within the range of from 1 to 50, 3 to 45, 5 to 40, 7 to 35, 10 to 30, 13 to 28, 15 to 26, or 17 to 25,% of the bulk volume of the macrosolid.
Further, in at least one major embodiment of the invention, it is preferred that, with increasing preference in the order given, at least 50, 60, 65, 76, 82, 87, 91, or 94% of the mass of the raw material in the particle bed utilized in a process according to this invention or present in a macrosolid according to this invention is selected from the group consisting of alkali metal and alkaline earth metal salts of sulfates (including hydrogen sulfates), carbonates (including hydrogen carbonates), silicates (including zeolites and metasilicates), phosphates (including hydrogen phosphates and condensed phosphates such as pyrophosphates and tripolyphosphates), hydroxides, borates, and citrates. For most purposes, the alkali metal salts, particularly the sodium and potassium salts, are preferred over the alkaline earth metal salts. Stoichiometric water of hydration and reversibly bound water in solid phases are both to be considered as part of the salt or hydroxide to which they are bound in determining what fraction of the raw material particle mass is selected from this group of preferred constituents.
In many embodiments of the invention, it has been found that the most desirable products are achieved when the content of water in the raw material particle bed is in the range from 1 to 25%, or more preferably from 2 to 20%, of the total mass. In determining the percentage of water in the total mass, any water of hydration present in the solids forming the raw material particle bed is counted as water, as are any liquid water present in the bed and any additional water that would be expelled as vapor from the initially solid part of the bed upon heating the bed to 100xc2x0 C., or to the maximum temperature actually reached within the particle bed during any part of the process, if such maximum temperature is known or controlled and is lower than 100xc2x0 C. (This value can be determined by measuring the expulsion of water vapor from a sample of the same raw material or raw material mixture, with the same particle size for each chemically distinct constituent, as forms the raw material particle bed used in the process according to the invention.) Alternatively, the water content can be measured by a modified Karl Fischer titration method.
The subinfrared electromagnetic radiation technique of the present invention may successfully be applied to a variety of cleaning formulations such as detergents or ware-washing, pre-washes, dishwasher detergents, carpet cleaners, floor care products, and general rinse/wash or all-purpose cleaners, and the like, for textiles or hard surfaces. An advantage of this technique is that the desired cleaner or detergent product may normally be obtained promptly upon the conclusion of the subinfrared electromagnetic radiation treatment.
The temperature of the particle bed at the beginning of subinfrared electromagnetic radiation treatment in a process according to this invention may be varied within wide limits, but for convenience and economy generally is preferred to be within the range of 15 to 50, more preferably from 20 to 35, still more preferably from 20 to 25, xc2x0 C. In addition, particularly when the raw materials used in the process include such chemicals as the alkali metal hydroxides with very high heats of solution in water, it is often advantageous in a process according to the invention to control the temperature during step (B) of the process by means of a device that discontinues or reduces the power of the subinfrared electromagnetic irradiation when a preset temperature of a suitable probe, which is electronically connected to the controls for generation of the SER radiation source used in the process and is physically located in close proximity to, preferably within 1 mm of, at least a part of the initial particle bed, is exceeded. Such preferences can not be stated on a general basis, as they depend on the particular materials processed, but guidelines can be obtained from the examples below.
If more than one chemical species makes up the solid raw material of the particle bed used in a process according to the invention, all the solid components are preferably mixed with one another to form a substantially homogeneous particle bed which is exposed to subinfrared electromagnetic radiation. Methods for such mixing will be generally known to those skilled in the art. For example, hand or mechanical stirrers and/or shakers may be used, the roughly mixed raw materials may be passed through a grinder or other comminution device, or the like.
The duration of exposure of the raw material mixture to subinfrared electromagnetic radiation according to the process of the current invention will depend upon a number of factors, the most important of which are discussed here. These include: the power of the SER source; the initial temperature of the raw materials in the particle bed; the water content of the raw material; the temperature-sensitivity, if any, of the raw materials; the shape or configuration of the container used; and the bulk of the material contained therein. When temperature-insensitive materials are used, however, it is the time duration required to achieve a sufficient temperaturexe2x80x94that is, the temperature at which the material is transformed from a bed of discrete particles into a unitary solid, or into a material that will constitute a unitary solid when cooled to a normal ambient temperaturexe2x80x94that will govern the duration of exposure of the raw material mixture to subinfrared electromagnetic radiation. The time of irradiation normally is preferably within the range of 5 seconds (hereinafter often abbreviated xe2x80x9csecxe2x80x9d) to 30 minutes (hereinafter often abbreviated xe2x80x9cminxe2x80x9d), or more preferably from 30 sec to 20 min.
For example, exposure to microwave radiation in a MLS-1200 T device (Bxc3xcchi) operating at 2450 MHz and 250 Watts for times from 2 to 4 minutes has been found to be sufficient to form 30 g tablets from raw materials that were stable to temperatures of up to 140-160 xc2x0 C., while 250 g blocks at the same power level needed at least 12 minutes. On the other hand, 30 g tablets can be formed in 15 seconds with the same microwave radiator at 1000 watts power. With a Hotpoint Model RE600002.92KW microwave generator rated and used at 240 watts power output, samples on the order of 400 g in size needed approximately 8 minutes, while 1-2 kg blocks may require 20 minutes or slightly more. Slightly longer times are needed if more temperature-sensitive raw materials are included in the particle bed.
Measurements of the dielectric parameters made by means of a Hewlett-Packard HP85070M Dielectric Probe Measurement System have demonstrated that radio wave irradiation is suitable for a number of raw material mixtures as shown in Table 1. In all three cases, the dielectric loss factor, E, in the radio wave range is higher than in the microwave range, suggesting that the time required to form macrosolids of a particular composition via radio wave irradiation according to the present invention should be less than the amount of time required for formation of microsolids via microwave radiation. With increasing preference in the order given, the time required with radio wave irradiation will be no more than 2.0, 1.75, 1.5, 1.25, 1.0, 0.75, 0.25 or 0.01 times the amount of time required for formation of microsolids via microwave radiation.
Macrosolid tablets and blocks according to the present invention preferably contain at least 0.1 percent, but more preferably at least 2% of water up to 15, or more preferably up to 11, % of water, the difference, if any, in water content before and after the subinfrared electromagnetic irradiation being believed to be due to the evolution of some water which usually accompanies the process. More preferably, the macrosolid products of some processes of the present invention contain from 0.5 to 10 percent of water, and still more preferably from 2 to 6 percent of water. The amount of water present in the macrosolid product may be determined by a conventional modified Karl Fischer titration, which is carried out as described in the indented paragraphs immediately following below. This method determines the amount of water volatilized from the sample by heating to 200xc2x0 C., including any water which is generated as a result of any possible decomposition reaction that occurs, (e.g., the decomposition of perborate).
The method is accurate to about 0.1% of water content.
Principle of the Method: Water is volatilized from the sample material to be tested by heating to 200xc2x0 C. in a special drying oven. The water vapor released is transferred in a dry nitrogen stream into an connected automatic Karl Fischer titrator and therein is titrated.
Apparatus; The apparatus consists of a special drying oven (Metrohmm(trademark) E 613) and an automatic Karl Fischer Titrator (e.g. Metrohm(trademark) E 452). The outlet from the oven is connected by a glass tube with an inlet capillary tube in the titration container of the titrator.
Nitrogen supply: Conventional compressed nitrogen in a steel tank is used. The pressure is reduced with the help of a pressure reducing valve to about 2.5 kilopascals/cm2. The outlet from the tank valve is connected via a hose, made of polyethylene and reinforced with glass fibers, to a gas flow meter, equipped with a control valve; after the gas flow meter, an empty safety washing bottle is placed in series, followed by a gas washing bottle containing concentrated sulfuric acid.
The washing bottle is connected to a tubing tee, from which one branch leads to a safety pressure-relief valve, e.g., a washing bottle highly overfilled with sulfuric acid, prior to which again an empty safety bottle should be inserted in a serial connection.
From the other branch leading from the tee, a connection with the drying oven is made via a glass tube, which is perfectly fitted and which is provided at the end with a spherical ground glass joint. No silicone hose or polyethylene hose may be used in place of the gas pipe, as otherwise at high air humidity water will diffuse into it and cause an erroneously high value for water.
Drying oven: The drying oven can be in essence used as delivered; however, the gas inlet and the gas outlet on the internal attachment piece should be provided with a spherical joint.
Connection between the drying oven and the Karl-Fischer-titrator: The connection between the drying oven and the titrator consists of a glass tube provided with spherical joints, the internal diameter of the pipe being 1.5-2 mm and the glass tube being attached to an inlet capillary tube of internal diameter of 1.5 mm, also provided also with a spherical joint. These parts are preferably manufactured specifically for this purpose and are adjusted to fit the spatial conditions and/or the titration container. The interconnecting tube may be omitted, if the spatial placement of the apparatus permits it. The connecting passageway between the oven and the titrator preferably is provided with a heating device, such as a strip heater or the like, which allows heating up to 80-100xc2x0 C., because the water can otherwise condense out in this zone.
Karl Fischer Titrator: A Karl Fischer titrator consists of 3 subunits, the titration container with a stirring device, the control and measuring electronics, and a dispenser, e.g., Metrohm Dosimat(trademark) E 655. The cover of the titration container is provided with 5 passages. From among them, the first opening is used for the reading electrode, the inlet capillary tube is led into the second opening, the third is provided with a rubber stopper with a hole drilled through, into which a thin polyethylene hose of internal diameter of about 1-2 mm is inserted deep enough that it reaches into the titration container up to about 3 cm above its bottom. The other end of the hose leads to a waste container for solvents. The inlet for the Karl Fischer reagent is connected with the fourth opening, and the fifth opening is provided with a ground joint stopcock. All passages must be sufficiently tightly fitting to avoid penetration by water vapor in the air.
The performance of water determination: The drying oven is preheated to 200xc2x0 C., and the heating of the connecting pipe between the oven and the titrator is also begun. The nitrogen feed is opened and controlled so that about 60 ml/min of nitrogen gas flow through the equipment, and the ground joint stopcock located in the cover of the titration container is also opened. Fifty ml of methanol is introduced into the titration container, the titrator is switched on and the methanol is titrated. A one-component Karl Fischer reagent is used as the titration agent, the pyridine-free Hydranal Composite(trademark) of Riedel de Haen Company having proved satisfactory. When the equipment is completely sealed, the blank consumption after the methanol titration must lie below 0.4 ml/h.
The titrator is set to switch off after 30 seconds of operation. With the help of a 50 xcexcl syringe, 50 xcexcl of water is added to the methanol previously titrated and the titration is started again. The coefficient xe2x80x9cFxe2x80x9d of the reagent solution is calculated from the equation:   F  =      10          consumption      ⁢              xe2x80x83            ⁢      reading      
This factor determination should be repeated at least three times, then an average from the obtained values should be calculated.
If the titration container after the completion of the titration is more than ⅔ full, the stopcock in the cover is closed. The overpressure, building up subsequently, will propel the liquid through the polyethylene hose into the solvent waste container, until the liquid level reaches the lower edge of the PE hose, then the stopcock in the cover is opened again.
Water determination in deterrents and cleaning agents: The sample the water content of which is to be determined is placed in a small steel boat (about 6 cm in lengthxc3x971.5 cm heightxc3x971 cm width). If no small steel boat is available, a small boat of comparable measurements can be shaped from a strip of aluminum foil of 0.5 mm thickness. Into the boat, 300-500 mg of the substance to be analyzed is weighed. For liquid alkaline samples a glazed porcelain boat should be substituted.
The small boat is introduced into the oven heated to 200xc2x0 C., the titrator is pre-set for 30 sec operation and the titration is started. During this process it should be carefully assured that the methanol used had already been titrated.
Depending on the substance, the titration is completed after 10 to 20 minutes, the titrator automatically switches itself off, and the value is recorded.
The water content of the substance is calculated as follows:       %    ⁢          xe2x80x83        ⁢          H      2        ⁢    O    =            ml      ⁢              xe2x80x83            ⁢              consumption        ·        F        ·        a        ·        100              E  
where a=theoretical titer of the Karl Fischer reagent, F=coefficient of Karl-Fischer-reagent, and E=sample mass in mg.
Reproducibility: The standard deviation for this determination, from 6 replication on one sample with a mean value of 20.5% water, is 1.1%. relative.
The invention includes within its scope the formation of macrosolid tablets or blocks which are formed from a mixture of raw materials containing all or nearly all of the necessary components for a cleaner formulation. In general, the ingredients and the relative proportions in which they are used in macrosolid cleaners according to this invention are substantially the same as those intended to be used for the same purposes in other solid cleaners of the prior art. The cleaner formulations suited to the present invention include all-purpose cleaners, detergents, industrial or institutional cleaners, ware-washing cleaners and automatic detergents for textile or hard-surface cleaning purposes. In one embodiment of the invention, it is possible to form macrosolid cleaner or macrosolid detergent tablets or blocks directly from raw material mixtures in disposable packaging, which constitutes the container during processing. Water-soluble films may be used for the disposable packaging, as discussed further below. The macrosolid tablets or blocks of the present invention may further comprise one part of a multiple-part cleaning combination.
In yet another embodiment of the invention, it is possible to after-treat tablets, blocks, or molded macrosolids in which a particular component, such as a microwave-sensitive substance such as an enzyme, or a surface coating designed to impart certain properties such as slower dissolution, for example, is excluded from the raw material mixture prior to treatment. The subinfrared electromagnetic radiation technique permits the use of these substances by incorporating them into the porous product from the end of step (B) in a process according to the invention as defined above, due to the porous structure in the subinfrared electromagnetic radiation macrosolid thus formed. Accordingly, substances such as those commonly used for coatings on cleaner blocks to protect against skin contact (i.e., materials such as poly{alkylene}s, especially ethylene, glycols, fatty acids, fatty acid amides, paraffin waxes, sorbitol, carbohydrates such as sucrose, and nonionic surfactants) can be successfully incorporated into the initial macrosolid product by dipping macrosolid blocks or tablets into appropriate liquid compositions and then drying some or all of the liquid constituents into a solid contained within the pores of the initially produced macrosolid.
Other conventional techniques such as spraying or otherwise applying the component onto the subinfrared electromagnetic radiation macrosolid are also possible due to the open space structure of the subinfrared electromagnetic radiation-formed products. On the other hand, if only a surface protective coating is desired, imbibition of the coating material into the pores and interstitial spaces of the macrosolid cleaners produced according to this invention may be minimized by coating with a relatively viscous coating material. Providing protection against unwanted contact with the skin of users of the macrosolid products of this invention, as with similar conventional products of the prior art, is important for safety when the cleaners are strongly alkaline in composition.
In this respect, the subinfrared electromagnetic radiation technique of the current invention presents a distinct advantage in the formation of macrosolid products over several prior art techniques. For example, in the formation of tablets by prior art techniques that involve elevated pressure, the structure of the resulting solid product is such that the solid cannot readily absorb additional materials once the tablet has been formed. Where an after-treatment or incorporation of a subinfrared electromagnetic radiation-sensitive or heat-sensitive material is desired, the open structure of the SER produced macrosolids permits incorporation of substances through permeation of these interstices. In this way, a broader range of products in macrosolid form, including products with most or all of the pores present in the initially formed macrosolid filled with some solid material, may be achieved with the SER process of the current invention than is possible with conventional techniques.
In addition to the preferred materials already described above, other materials that are suitable and useful for at least some applications as part of the raw material particle bed for a process according to this invention include the usual non-ionic, anionic, cationic and zwitterionic surfactants and mixtures thereof. (Cationic and amphoteric surfactants, and other materials capable of acid-base neutralization reactions with the alkaline materials that usually make up the bulk of the alkaline cleaner products according to the invention, should be used only with caution, because the exothermic neutralization reaction can cause unwanted temperature irregularities during the subinfrared electromagnetic radiation processing, as a result of conversion of formerly solid acidic and alkaline materials in the raw materials into molten or dissolved phases.) The surfactant or surfactants chosen for use as constituents of the particle bed in accordance with the present invention in general comprise no more than 25%, and preferably no more than 15%, of the total raw material mixture. However, if desired as it is for certain products according to the invention, additional surfactant can be added by imbibition into the pores and interstitial spaces of the initially produced macrosolid product according to this invention.
Silicates that are useful in the process of the present invention include alkali metal metasilicates, where the alkali metal is preferably sodium. Preferred sodium metasilicates include the anhydrous form as well as sodium metasilicate.5H2O. Silicates may preferably be present according to the present invention in amounts from 0 to 80%. Hydrated forms of sodium silicate, particularly sodium silicate.5H2O, were found to aid in the SER solidifying process when used in ranges of at least 1 percent but less than 50 percent, and preferably between 1 to 30 percent.
Phosphates that may be used in the subinfrared electromagnetic radiation process of the present invention include alkali metal tripolyphosphates, hydrogen phosphates and pyrophosphates, either in anhydrous or hydrated forms or a combination thereof. The preferred alkali metal is sodium. Preferred sodium phosphates include anhydrous sodium tripolyphosphate (xe2x80x9cSTPPxe2x80x9d), STPP.6H2O, and trisodium phosphate (TSP).10H2O. Phosphates may preferably be used in amounts of up to 80%. Borates that may be used in the SER process of the present invention include alkali metal borates, either in the hydrous or anhydrous forms or a combination thereof. The alkali metal is preferably sodium. Preferred sodium borates include sodium borate.10H2O (Borax). Borates may preferably be present in amounts of up to 20%, and thus are preferably used in combination with at least one other raw material.
Carbonates and bicarbonates that may be used in the SER process of the present invention include alkali metal carbonates and alkali metal bicarbonates, either in the hydrous or anhydrous forms, or a combination thereof. The alkali metal is preferably sodium or potassium. Preferred sodium carbonates include anhydrous sodium carbonate and sodium carbonate.10H2O. The preferred bicarbonate is anhydrous, and sodium is the preferred alkali metal. Suitably hydrated carbonates may preferably be used in amounts of up to 100% of the total raw materials mixture. Bicarbonates, which are also known as hydrogen carbonates, may preferably be used in amounts of up to 40%, and are thus preferably used in combination with at least one other raw material. Where bicarbonates are used in formulations for promoting hygiene, they are preferably used in amounts of up to 20%. Where bicarbonates are used for dishwasher formulations, they are preferably used in amounts from 5 to 40%. In certain cases, it is preferable to avoid using bicarbonates in the same raw material mixture as either carbonates or citrates.
Alkali metal hydroxides may preferably be present in amounts of up to 80 percent, and more preferably from 2 to 70 percent. Preferred hydroxides include sodium and potassium hydroxide. For applications in the kitchen hygiene area, or wherever tablets with high alkali content are especially desired, the process of the present invention offers several advantages over prior art techniques. The manufacture of solids containing high alkali content is not practical using pressing techniques of the prior art, for example, due to moisture accumulation which occurs on the pressing apparatus during the process. This is particularly bothersome where formulations containing both sodium hydroxide and perborate are desired, to the extent that the manufacture of pressed tablets containing such compositions is believed never to have been practical. Furthermore, it is not possible to mechanically press tablets with high alkali content when there is greater than 80% moisture present in the air. The microwave process of the present invention is not affected by either of these conditions, and macrosolid tablets that are not only high in alkali content, but that also contain perborate, have successfully been obtained.
Sulfates that may be used in the subinfrared electromagnetic radiation process of the present invention include alkali metal sulfates, alkaline earth sulfates and hydrogen sulfates, although calcium sulfate is only rarely used because of its low solubility. Alkali metal sulfates are preferably used in the non-hydrated form; alkaline earth sulfates are preferably used in the hydrated form. Sodium is the preferred alkali metal for alkali metal sulfates, and magnesium is the preferred alkaline earth metal for alkaline earth sulfates. When an alkaline earth sulfate is used in the hydrated form, the preferred alkaline earth sulfate is MgSO4.7H2O. Alkali or alkaline earth sulfates may preferably be used in amounts of up to 80% of the raw material, but more preferably are used in amounts of 1 to 30%.
Citrates that may be used in the subinfrared electromagnetic radiation process of the present invention include hydrated and non-hydrated alkali metal citrates, and sodium is the preferred alkali metal. Especially preferred citrates are the mono-, di-, and penta-hydrates of sodium citrate. Alkali metal citrates may preferably be present in amounts of up to 95 percent of the total solid raw material, and are especially preferably used in amounts of 30 to 50% for general cleaning formulations. With respect to some formulations for use in the dishwashing area, citrates are more preferably used in amounts of 80 to 90% of the total solid raw material.
Nonionic surfactants that may effectively be used in the subinfrared electromagnetic radiation process of the present invention include those commonly used solid cleaners of similar chemical composition in the prior art, such as alkyl-, arylalkyl-, alkylaryl-, and aryl-polyoxyalkylenes, esters and amides of polyoxyalkylated alcohols, and poly{alkyl glucosides}, preferably ethoxylated fatty alcohols and ethoxylated alkyl phenols. In some particular applications, the most preferred fatty alcohol is tallow alcohol condensed with an average of 14 moles of ethylene oxide per mole of tallow alcohol (this alcohol-ether is hereinafter often abbreviated xe2x80x9cTA 14xe2x80x9d) and the preferred ethoxylates are nonylphenol ethoxylates such as NPE 9.5 (with an average of 9.5 molecules of EO per molecule of nonyl phenol). Non-ionic surfactants may preferably be present in amounts of up to 25 percent, and more preferably in amounts of 0.1 to 15%.
Anionic surfactants that may be used in the practice of the present invention include fatty acid sulfates, sarcosides, sulfonamidocarboxylates, salts of partial organic esters of sulfuric and phosphoric acids, salts of sulfated esters and amides of carboxylic acids, with a preferred group including Mersolat(trademark) 95 and linear alkylbenzene sulphonates. Anionic surfactants may preferably be present in amounts up to 15 percent, and more preferably from 0.1 to 5%.
Cationic and zwitterionic surfactants may preferably be present in amounts of from 0.1 to 25%, and more preferably from 1 to 15% of the total raw material mixture. Typical raw materials of this type, all of which are suitable for use in this invention, include amine oxides, amidazolinocarboxylates, betaines, and aminocarboxylic acids for zwitterionic surfactants; and primary, secondary, tertiary, and quaternary ammonium salts, such as alkanolammonium, imidazolinium, quinolinium and isoquinolinium salts, and thiazolinium salts as well as the more common fatty ammonium salts, along with sulfonium and tropylium salts, for cationic surfactants.
Optionally, the raw material mixture of the current invention may also contain additives and auxiliaries. Additives preferably are present in amounts not greater than 60%, more preferably not greater than 40%, or still more preferably in amounts of 0.5 to 15%. Examples of suitable additives include, but are not necessarily limited to: active oxygen sources and oxidizing materials; active chlorine sources and chlorine-containing materials; enzymes; sequestrants; fillers and builders; abrasives; turbidity promoters; dispersants and dispersing agents; corrosion inhibitors; and disinfectants.
Auxiliaries may preferably be present in amounts of up to 10%, and are more preferably used in amounts of 0.1 to 2%. Examples of auxiliaries include, but are not necessarily limited to: perfumes; dyes and pigments; defoamers and foam inhibitors; solubilizers; anti-redeposition agents, and dye transfer inhibitors.
With respect to additives that may be used in the current invention, chlorine and oxygen sources may be effectively used either coated or uncoated, and may be added directly to the raw material mixture in either form. Alternately, these materials may be incorporated into the subinfrared electromagnetic radiation-formed product subsequent to initial macrosolid formation. Another advantage of the present invention, therefore, is that unlike prior art techniques for casting or molding solid detergents, the SER process of the present invention does not require that chlorine-containing components be included as a preformed plug, cartridge, or core.
Typical chlorine sources that may be effectively used according to the present invention include chloroisocyanurates such as di- or tri-chloroisocyanurates, and polychloroisocyanuric acids. Two examples of the latter include CDB-56(trademark) (available from Olin) and ACL-90(trademark) (available from Monsanto). In the present invention, chlorine sources may preferably be present in amounts of up to 30 percent, and more preferably from 1 to 5 percent. It has been found that raw material mixtures that incorporate chlorine sources tend to exhibit temperature sensitivity during the microwave process, and where such materials are used, temperature controls should be preferably implemented such that the raw material mixture does not exceed a particular temperature. In the case of chlorine source materials, it was determined that temperatures should preferably be kept under approximately 383xc2x0 K. (110xc2x0 C.).
Although active oxygen sources are typically used in powder or granular detergent formulations, their use in uncoated form in the present process is not preferred, although both coated and uncoated forms have successfully been used in the present invention, with careful temperature control. If the raw material mixture achieves too high a temperature during certain subinfrared electromagnetic radiation treatments, uncoated oxygen sources or oxidizing sources such as sodium perborate or sodium percarbonate have been observed to decompose, accompanied by the evolution of gas, which caused foaming in the sample being irradiated. Accordingly, temperatures for raw material mixtures containing oxygen sources should preferably be kept under approximately 343xc2x0 K. (70xc2x0 C.) during microwave processing according to this invention.
Coated oxygen sources, however, have surprisingly been found to demonstrate good compatibility with the subinfrared electromagnetic radiation technique, and tablets and blocks containing coated perborate or coated percarbonate have successfully been produced directly from pre-mixtures containing these raw materials. Coated forms of oxygen sources are especially preferred in applications where strongly alkaline formulations are desired. The use of these coated compounds as an active oxygen source in the process of the present invention is therefore preferred. Perborates, percarbonates, or other conventional oxygen sources may preferably be present in amounts up to 30 percent, and more preferably from about 5 to about 25 percent. Perborates preferably used have the general formula MBO3.yH2O, where M is an alkali metal, most preferably sodium, and y is a number from 1 to 4.
Also belonging to the category of additives in the current invention are enzymes. Where enzymes are used directly in the raw material mixture of the invention in solid form, they preferably feature a coating or encapsulation. Uncoated enzymes that are commercially available in fluid form may also be used. Alternately, enzyme solutions may also be incorporated into the macrosolid subinfrared electromagnetic radiation tablet or block at a point in the process subsequent to SER treatment. This incorporation is possible in the present invention because of pores and/or interstitial spaces which are formed in the macrosolids during exposure to SER radiation. These internal spaces permit the adsorption of enzymes, or any other material, directly into the macrosolid tablet or block. According to one embodiment of the present invention, where the final product contains enzymes, they may preferably be either amylases or proteases. If desired, the enzymes may be conventionally coated, as with sulfate coatings, to protect them from adverse interactions with other constituents of the raw materials used. Enzymes may preferably be present in amounts up to 10 percent, and more preferably from 0.1 to 5 percent.
The technique of the present invention represents a distinct advantage over melt-block processes for the production of enzyme containing detergent formulations of the prior art. Since the subinfrared electromagnetic radiation process of the current invention may be implemented for short durationsxe2x80x94minutes or even seconds, depending upon composition and sample size as discussed abovexe2x80x94enzymes may be directly incorporated into the macrosolids produced by this technique.
As indicated above, other conventional detergent or cleaner components may also be used as additives to the raw materials mixtures according to the subinfrared electromagnetic radiation process of the invention in addition to oxygen sources, chlorine sources, and enzymes. These substances include: sequestrants; fillers and builders; abrasives; turbidity promoters, dispersants and dispersing agents; corrosion inhibitors; heavy metal scavengers; waxes; and disinfecting substances. Examples of builders are phosphonates and polycarboxylates (i.e., alkali metal salts of homo- or co-polymers of acrylic acids), which may preferably be present in amounts of up to 30 percent, and are more preferably used in amounts of 1 to 15 percent.
Abrasives that may preferably be used according to the present invention include such substances as marble, quartz, and alumina powders, preferably of the polishing grit or particle size, and they preferably are present in amounts not greater than 60%, or more preferably not greater than 40%. In one particular embodiment of the present invention, it is possible to include abrasives of varying size directly into the raw material particle bed prior to subinfrared electromagnetic radiation treatment, based on the application desired for the final product. The incorporation of abrasives directly into the particle bed therefore constitutes an advantage over milk-type scouring products (also called scouring creams) of the prior art. Prior art products often have sedimentation problems due to the presence of scouring powders and granular solids in the milk liquor, which settle with time. In order to overcome these problems, prior art scouring creams often require the use of suspension agents, which subsequently introduces a second problem. That is, the use of a second, surfactant-containing cleaning product is often required in order to wash away the scouring powder and granules after use of the first scouring cream. This may further introduce rinsing problems. The SER technique of the present invention avoids both problems, as scouring powders and granular solids of different sizes may be incorporated, along with a surfactant, directly into a raw material pre-mix formulation. Not only does this reduce the number of steps that may be required in a particular cleaning operation, it also reduces the number of items and therefore attendant packaging materials required.
Turbidity promoters include preferred styrene-vinylpyrrolidone copolymers in addition to other usual turbidity promoters. Dispersants include, among known dispersants, especially naphthalene sulfonic acid condensation products. Preferred corrosion inhibitors include such materials as technical 2-buten-1,4-diols (available from Colus). Preferred heavy metal scavengers include phosphonates, nitrilotriacetic acid (xe2x80x9cNTAxe2x80x9d), and ethylene diamine tetraacetic acid (xe2x80x9cEDTAxe2x80x9d). Waxes preferably are present, if at all, in amounts not greater than 5 percent, and more preferably in amounts from about 0.1 to 2 percent. Disinfectants include the normal disinfecting substances that would be known by one familiar with the cleaning arts, and may be used in conventional amounts.
Perfumes, dyes and pigments may preferably be used in Is amounts of up to 3 percent, and more preferably from 0.001 to 1 percent. Where foam inhibitors or defoamers are used, they may be mixed directly with the raw materials of the particle bed. One advantage over prior art techniques of casting or molding solid detergents is that according to the subinfrared electromagnetic radiation process of the present invention, it is not necessary to include the foam inhibitor component as a preformed plug or core, as has been taught in some prior art.
Dedusters and defoamers such as paraffin oil and silicone oil respectively, for example, may be present in amounts of up to 5 percent, and are preferably present in amounts of 0.1 to 3 percent. Anti-redeposition agents may be present in amounts of up to 5 percent, and are preferably present in amounts of 0.1 to 3 percent. The preferred anti-deposition agent is carboxymethyl cellulose (CMC). The preferred solubilizers are alkyl carbonic acids, cumene sulfonates, and toluene sulfonates, although other solubilizers known to those familiar with the cleaner arts are also suitable. Dye transfer inhibitors may also be used in amounts of up to 5 percent, and are preferably present in amounts of 0.1 to 3 percent. The preferred dye transfer inhibitor is poly{vinyl pyrrolidone} (xe2x80x9cPVPxe2x80x9d).
In certain embodiments of the present invention, a separate liquid phase component can be used in combination with a macrosolid component produced by the subinfrared electromagnetic radiation process of the invention, resulting in a two component or xe2x80x9cdual-packxe2x80x9d product system. Generally, in the liquid phase component of such dual-packs, the ingredients which are used according to this invention are substantially the same as those intended to be used for the same purposes in other liquid cleaners of the prior art. The proportions can be varied therefrom, however, as it is not necessary to include waterxe2x80x94or the same amount of water as is required in prior art liquid compositionsxe2x80x94as water will be introduced to the liquid component and macrosolid just prior to use. Moreover, another feature of such a dual-pack embodiment is that it is possible to manufacture more concentrated products than is possible in the prior art, without having to compromise final product quality.
In certain preferred embodiments, the liquids used in the dual-pack embodiment are selected from the group consisting of known nitrogen-containing solvents such as ammonium hydroxide or ethanolamines, propylene glycol ethers and glycol ether solvents such as propasol solvent B (Union Carbide), monophenyl glycols such as phenoxy ethanol, and salts of cumene sulfonates, toluene and xylene sulfonates, with the sodium salt generally being the preferred constituent, such as sodium cumene-sulfonate (40% aqueous solution). In general, all the usual water-dispersable materials and solubilizing agents, such as alcohols, can also be used.
It is also anticipated that for certain applications, it may be desirable to include certain dissolved solids in the liquid component of the dual-pack embodiment according to the present invention. Such may be the case, for example, if a material is not amenable to treatment by subinfrared electromagnetic radiation and therefore cannot be incorporated into a macrosolid produced according to the process of the invention, or for reasons of convenience or handling, it is more advantageous to include such material in the liquid component phase of the dual-pack product. Examples of such materials include low-boiling alcohols, ethanolamines and perfumes with low boiling points that can be evaporated off during treatment by subinfrared electromagnetic radiation. In other instances, it may be desirable to both dissolve certain solids in the liquid component and also include them in the macrosolid component of the dual-pack product. One example of such a material is potassium hydroxide. In yet additional embodiments of the invention, it is possible to combine a macrosolid cleaner with different dual-pack fluid components, or to use a particular dual-pack fluid component with different macrosolid cleaners in order to achieve a desired result. These and other variations will be apparent to those skilled in the pertinent art.
The maximum temperature that is acceptable for the subinfrared electromagnetic radiation process of the present invention will be below the decomposition temperature of any temperature-sensitive materials, such as oxidizing materials or chlorine-containing materials, that are present in the raw material processed.
In contrast to the press-forming of detergent tablets, it has been found that the subinfrared electromagnetic radiation process of the present invention can be used to produce macrosolid products of virtually unlimited size. It will be appreciated by those knowledgeable in the relevant field, however, that certain practical constraints exist. The power of the SER source, the size of the SER chamber, and the internal temperature that can be attained in a sample within a convenient and economically practical amount of time are all factors that determine the optimal size particle bed to be used. For example, it has been successfully demonstrated that raw material samples ranging from 10 grams to several thousand grams can be conveniently and reproducibly exposed to microwave radiation for times as short as one to two minutes up to approximately twenty minutes or in order to yield tablets or block macrosolids according to the process of the present invention. The descriptions and examples contained below contain further guides for successfully practicing the subinfrared electromagnetic radiation method of the present invention.
It has also been found that the shape of the container used to hold the particulate starting raw materials can be optimized in order to enable production of the most advantageously stable macrosolid tablet or block formed. The container used is generally open at the top to permit the escape of volatilized water that is generated from the sample during subinfrared electromagnetic radiation treatment. Where the open end or open portion of a container has an area xe2x80x9cAxe2x80x9d, the ratio of the square root of A to the depth xe2x80x9cDxe2x80x9d of the particle bed, i.e., the maximum distance, in a direction perpendicular to the plane of the area xe2x80x9cAxe2x80x9d, that is within the particle bed, is preferably within the range from 1:2 to 10:1, or more preferably from 1:1 to 5:1. This range of ratios permits formation of macrosolid blocks as well as xe2x80x9cflatterxe2x80x9d disc-shaped macrosolids that are surprisingly strong and exhibit good integral strength, without compromising physical strength, so that the product can be conveniently handled without being readily broken or producing much powder.
Virtually any configuration may be used for a container in order to produce a macrosolid tablet or block according to the present invention. A variety of particular forms may be desired, for instance, based upon different machine applications. The dimensional constraints for the tablet or block will depend upon the path that water molecules must travel in order to escape from the bulk raw material mixture as part of the subinfrared electromagnetic radiation process, and the length of time that exposure to subinfrared electromagnetic radiation is needed before exceeding the temperature stability of any of the raw materials. Where a particular cleaner tablet or block shape is desired that does not meet the above optimal dimension criteria, such shape is still possible, providing that there are sufficient openings made in the sides or at the periphery of the container to permit the evolution of water molecules from the bulk of the raw material mixture during SER treatment.
The method of the invention is readily adapted for use on a continuous basis, wherein a plurality of initial particle beds in a plurality of containers is continuously introduced, by a conventional conveyor for example, into a subinfrared electromagnetic radiation heating zone and the resultant macrosolid product is continuously removed from said zone, or from an intermediate cooling zone, in macrosolid form. Not only is it possible to employ reusable containers with the process of the present invention, but actual shipping or handling containers can also be used as the containers during the subinfrared electromagnetic radiation processing in order to streamline the production and packaging processes.
In one embodiment of the present invention, a container of a water-soluble film material is used. The container preferably retains an opening to permit the evolution of water molecules from the raw materials during subinfrared electromagnetic radiation treatment, and can be sealed in a subsequent step. In yet another embodiment of the present invention, the container is a light-weight packaging or a thin polymer-type material, which may be especially desirable for dispensing purposes in connection with the use of larger block macrosolids. In still another embodiment of the present invention; rigid or flexible bags are used as containers.
In one embodiment of the invention when the container is a reusable one, it is advantageous to use a container with walls that are capable of reversibly adsorbing and/or absorbing water. This promotes more rapid solidification of the particle beds used in such containers. In a variation, several such containers on a continuous belt that circulates in and out of the subinfrared electromagnetic radiation cavity, and optionally to another source of high temperature to drive out water from the container walls while the containers are empty, are used.
The dimensions of the final tablet or block macrosolid that is produced according to the present invention will, as indicated above, depend upon the initial sample size and the shape of the receptacle mold or container used. Thus, a sample of 30 g of raw material that was exposed to microwave radiation in a 100 ml Petri dish gave rise to a tablet on the order of 5.4 centimeters (hereinafter often abbreviated xe2x80x9ccmxe2x80x9d) in diameter by approximately 2.0 cm in height. A macrosolid cylindrical block formed from a 250 g sample had dimensions of approximately 6 cm for both diameter and height. The dimensions for a cylindrical block formed from 1 kilogram of raw materials were approximately 16 cm in diameter by 4.5 cm. Dimensions for other size tablets and blocks may be found in the examples below.
The tablet or block macrosolid formed via the subinfrared electromagnetic radiation process may usually be conveniently and readily removed from a reusable solidifying container by merely inverting the container to dislodge the item thus produced. If desired, a releasing agent such as a silicone spray may also be used to pre-treat the mold before the raw material mixture is introduced in to the mold.
As already briefly noted above, it has been surprisingly found that some of the macrosolid tablets or blocks formed according to the subinfrared electromagnetic radiation process of the current invention with conventional water soluble alkaline cleaner materials exhibit remarkably rapid dissolution, or a combination of dissolution and mechanical disintegration upon exposure to water. In comparison studies, microwave macrosolids produced by the current invention exhibited dissolution rates that were at least an order of magnitude faster than commercially available solids. Thus, blocks on the order of hundreds of grams up to kilogram size have been shown to disrupt and dissolve readily when dropped into a beaker of water. One 400 g sample fell completely apart and was entirely flushed out of the dispensing chamber into which it had been placed. The bottom of the sink into which the material was dispensed had a build-up of undissolved material from the block. The macrosolid block therefore allows for easier handling than a powder and has similarxe2x80x94if not betterxe2x80x94dissolving characteristics. This further provides for less opportunity for operator exposure to partially dissolved tablets or blocks. From the foregoing, the fact that such subinfrared electromagnetic radiation-produced macrosolid blocks offer certain conveniences in handling and shipping would therefore be appreciated by those knowledgeable in this field. Specific comparison data for relative dissolution/disintegration rates are given in Table 2 below.
For additional handling convenience or modification of the block properties, it was discovered that a thin coating layer of poly{ethylene glycol} (hereinafter often abbreviated xe2x80x9cPEGxe2x80x9d) can be introduced into blocks consolidated via the subinfrared electromagnetic radiation technique of the present invention. By way of example, either the blocks were dipped into melted PEG after microwave treatment, or PEG was added to the raw materials in powder or flake form prior to microwave treatment. In this manner, PEG of various molecular weights may be incorporated into larger macrosolid blocks. In particular, PEG 900, 1450, 3350, 8000,and 20,000 (the numbers representing weight average molecular weights of the PEG) all gave acceptable results via either of the above incorporation techniques. It should also be recognized that, where desired, a combination of the dipping or incorporation techniques is also possible, and would be consistent with the teaching of the present invention.
Macrosolid blocks that were dipped into PEG were exposed to the molten substance for times that varied from approximately five to approximately sixty seconds. One hundred gram samples were prepared that contained an additional 10 to 36 g of PEG in the raw materials prior to microwave treatment. Dispensing rates for PEG-treated blocksxe2x80x94either coated with PEG or with PEG incorporated thereinxe2x80x94were then compared. In general, PEG coated blocks dispensed at a somewhat slower rate than analogous blocks containing solidified PEG in the raw materials.
While the following processes are described with reference to specific components, it should be understood that other components and similar processes can be used together with the subinfrared electromagnetic radiation process of the present invention in order to produce cleaners or detergents in the form of tablet or block macrosolids.
Typically, the starting raw materials for the desired cleaner or detergent formulation are mixed or combined together at ambient temperatures to form a pre-mix, which is introduced into a reusable mold or a receiving container device. The minimum amount of solid raw material which is normally used to form a macrosolid tablet or block according to the present invention is one half gram (0.5 g).
The small amount of water required for the process of the invention is usually already present in the solid raw materials. Where this is not the case, water may be added to the raw materials prior to subinfrared electromagnetic radiation treatment to provide the water required, depending upon the desired formulation. Where well-characterized hydrates are used, and the other raw materials are not strongly hygroscopic, the water content may be calculated based on the chemical formula and percent of the well-characterized hydrated raw material(s) used in the pre-mix.
As will be apparent to those knowledgeable in the field, in certain instances it may be desirable to pre-heat one or more raw materials or portions thereof prior to subinfrared electromagnetic radiation treatment. Furthermore, preformed cores or plugs such as those described in U.S. Re. Pat. No. 32,763 (Fernholz, et al.) can be introduced into the container for the raw material particle bed, before or after the raw material mixture has been introduced into the mold, but before it is exposed to SER radiation. Alternately, it may also be desirable to after-treat the macrosolid block or tablet thus formed via a subsequent technique such as dipping, spraying or coating, etc., as discussed above. Such after-treatment may be desirable where, for instance, a particular desired component of the final product is not stable to SER irradiation, or a particular characteristic enhancement or deterrent is desired.
The stability and uniformity of the subinfrared electromagnetic radiation in the SER chamber or at the point of treatment is an important factor for the successful practical application of the process according to the present invention. A non-uniform distribution of subinfrared electromagnetic radiation energy has been observed to create localized hot spots in the raw materials which can lead to uneven heating and temperature xe2x80x9crunaway.xe2x80x9d Furthermore, a constant and non-varying SER radiation intensity from one SER treatment to the next is important, so that raw material formulations may be repeatedly and reproducibly solidified by the technique. It is also possible, and in keeping with the teaching of the present invention, that using more than one power setting for different time periods, or xe2x80x9cpulsingxe2x80x9d a sample with different power SER radiation, may also be desirable, depending upon the desired application and raw materials used. In such instances, the amount of time required to form a macrosolid tablet or block would be dependent on the sample weight, the size and shape of the container used, and either penetration depth of subinfrared electromagnetic radiation or the path length required for loss of volatilized water. In those instances where larger amounts of water may be evolved during SER treatment, it may be desirable to sweep the treatment chamber with air or an appropriate inert gas so as to prevent condensation of undesired water within the chamber. With samples on the order of 30 g size, this was not necessary. However, even with the smaller 30 g tablets, where production conditions require large numbers of samples to be simultaneously treated, then, depending upon the size and configuration of the chamber and container in which the samples are exposed to subinfrared electromagnetic radiation, the use of a sweeping stream may be advantageous.